This invention relates to thin film battery construction, and more particularly to a method of producing thin film batteries.
Thin film lithium batteries have existed for many years. These batteries have high energy and power densities as well as the capability of being cycled thousands of times. The active battery components are a lithium intercalation metal oxide cathodes, e.g. V2O5, LiNiO2, LiMn2O4 or LiCoO2, and a lithium metal anode or other suitable lithium intercalation anode material separated by an electrolyte. It has been found that the high energy and power densities of lithium cathodes make them attractive as compact rechargeable power sources for application in a variety of electronic devices.
Thin film batteries are ideally suited for use within small electronic devices. Because of the requirements associated with such small electronic devices it is imperative that the battery which powers them be made as small as possible in order to provide the greatest volumetric power density. However, thin film batteries today are manufactured upon substrates of inactive material which support the other battery components during the manufacturing process. These substrates, the thinnest of which is believed to be between 5-10 microns in thickness, oftentimes amount to a large amount of the battery""s volume. As such, the volumetric power density is greatly reduced due to the mere existence of these substrate.
Accordingly, it is seen that a need remains for a method of producing a thin film battery with a greater volume of active material and a minimal volume of inactive material in order to achieve a high volumetric power density. It is to the provision of such therefore that the present invention is primarily directed.
In a preferred form of the invention a method of producing a method of producing a thin film battery cell comprises the steps of providing a supporting substrate, depositing a cathode upon the substrate, depositing an electrolyte upon the cathode, and removing the substrate from the cathode.